Multi-material and/or multi-color injection molding applications typically require an injection molding machine that has two or more injection units for delivering the two or more materials and/or colors to an injection molding system, which includes, inter alia, a hot-half, coupled to the molding machine stationary platen, generally associated with the cavity side of the injection mold, including a hot runner system having one or more injection molding manifolds and injection molding nozzles, and a cold-half, coupled to the molding machine moving platen, generally associated with the core side of the injection mold and the part ejection system. During operation, the hot-half and cold-half are urged together by the injection molding machine to define the mold cavities into which a melt steam of moldable material is injected to create a desired form. Such multi-injection unit molding machines are a significant capitol investment for molders due to the increased complexity involved in having multiple injection units associated therewith.
Auxiliary injection units have been developed that may be used with injection molding machines having a single injection unit in order to provide a means for processing the additional material and/or color required for multi-material and/or multi-color injection molding applications. Such auxiliary injection units may be attached to the injection molding machine and/or the injection molding system such that the extruder nozzle of the auxiliary injection unit, or more particularly the nozzle tip associated therewith, interfaces with the second material inlet component of the injection molding system via a carriage stroke. Such an interfacing arrangement between the auxiliary injection unit and the injection molding system permits convenient open-air purging of the auxiliary injection unit molding material when, for example, a material and/or color change is desired. However, due to the necessary force associated with the carriage stroke, in order to maintain a seal between the tip of the auxiliary injection unit nozzle and the second material inlet component during injection of the plasticized melt, bulky frames or other support mechanisms are required. As well, linkages, drive units, and controls to allow for movement of the auxiliary injection unit relative to the injection molding machine and/or the injection molding system are also required. As such, many auxiliary injection units have extra components/controls that not only make them more complex with a larger overall size and weight, but also increase the expense and maintenance cost/frequency of the units.
As such, a need exists in the art for an auxiliary injection unit that provides one or more of the following benefits: overall height and/or weight reduction, simplified extruder design, elimination of carriage stroke and associated sealing force mechanism, and/or addresses one or more of the deficiencies noted above with respect to the prior art systems.